After closing a $150M Series C, Chesky asked Peter Thiel for his single most important piece of advice. Thiel's answer: "Don't fuck up the culture." Thiel's cynical view was that it's practically inevitable once a company reaches a certain size — but defending culture was a major reason he invested.

"Culture is simply a shared way of doing something with passion."

"Culture is a thousand things, a thousand times. It's living the core values when you hire; when you write an email; when you are working on a project; when you are walking in the hall."

The stronger the culture, the less corporate process a company needs. Families and tribes don't require much process because trust supersedes it; weak-culture organizations compensate with heavy, precise rules.

If Airbnb exists in 100 years, it won't be a booking website for homes — products will have evolved past recognition. What endures across century-long companies is culture, which is "the foundation for all future innovation. If you break the culture, you break the machine that creates your products."

Chesky's challenge to himself after Thiel's warning: how many CEOs actually focus on culture above all else? Is it the metric they measure closest? Is it what they spend most of their hours on each week? Growth, shipping, and government relations problems come and go — "but culture is forever."